The overall objective of this proposed research plan is to determine the effect of aging on the feeding behavior of two fly species by concentrating on the major peripheral receptor system (tarsal and labellar chemoreceptors) involved in food acceptance and intake. Investigations are designed to elucidate the various changes in receptor (tarsal and labellar chemoreceptor) functioning that are associated with aging, to evaluate how these changes influence the overall food intake of aged flies and to determine how this relates to senescence and eventually death. A concentrated effort will be made to uncover the adaptive mechanisms utilized by the fly that provides for maintaining homeostasis through life. Behavioral monitoring of acceptance thresholds will be employed along with individual determination of intakes at various physiological and aged conditions. Receptor functioning (operativity and sensitivity) will be determined using electrophysiological techniques that employ using glass micropipette electrodes filled with the testing solutions that are placed over the receptor. Receptor functioning will be recorded visually on a screen using an oscilloscope and permanently on tape using a continuous recording linograph camera.